Common sense and basic Newtonian physics tells us that a die can
transfer its design to a planchet only when there is resistance to its
impact from the opposite side. Without such direct resistance, no
design should form on either face.
Although a coinage press cannot violate Newton’s laws, there are
some circumstances in which a die will transfer its design without a
direct opposing force. The necessary resistance is instead delivered
through an indirect route.
One example is the Type II stutter strike, in which a planchet
tips up into the path of the descending hammer as the result of
unevenly and prematurely applied striking pressure caused by the
presence of an intrusive planchet, coin or foreign object at the
In a Type III stutter strike, a tiny bit of die struck design is
left on the apex of a bent coin. Here the resistance is supplied by a
temporary arch, the sides of which briefly resist flattening out (see
Collectors’ Clearinghouse, Dec. 28, 2009, and July 25, 2011).
These are not the only circumstances that leave die-struck design
elements on one face and nothing but the original unstruck surface of
the planchet on the opposite face. When crushed flat against a gaping
hole, a planchet will sometimes squeeze through in the direction of
the hammer or anvil die, with only the apex of the extruded metal
making direct contact with the die. Designated “extrusion strikes,”
this category of “one-sided” strike has been previously discussed in
the March/April 2004 Errorscope and in the Fall 2007 Mint Error News
In one variation of the extrusion strike, coin metal protrudes
through a gap in an object interposed between planchet and die. An
example is seen here in a 1983 Washington quarter dollar. It was
struck through a dislodged and torn late-stage die cap. Coin metal
protruded through the triangular tear. The apex of the bulge made
direct contact with the obverse die, picking up a weak impression of
the base of Washington’s bust and the date. The featureless area on
the opposite face is concave and carries the original tumbling marks
of the unstruck planchet.
A coin struck in-collar against an incomplete planchet experiences
the same conditions. Such coins often show variable development of an
extrusion strike as coin metal is forced through the gap in the
incomplete planchet and into the path of the die.
A gap in the die itself prompted formation of an extrusion strike
an undated quarter dollar illustrated this week. It shows a cud
(marginal die break) on the obverse face and a retained cud on the
reverse face. The retained cud has left most of the letters of united
sitting on a low plateau. This part of the die broke off but was held
in place by the collar. Instead, the die fragment simply sank below
the plane of the die face. Coin metal bulged into the recess, leaving
a full die-struck design on the reverse face and a small, featureless
hollow on the obverse face.
A third scenario associated with extrusion strikes involves a
planchet that is overlain by a coin, planchet or foreign object and
simultaneously confined by a partly deployed collar. Coin metal —
trapped between the intrusive object and the immobile collar — bulges
into the gap between the two, contacting the hammer die. A New Jersey
quarter dollar illustrates what can happen. It has an 80 percent
indent on the obverse face and shows a partial collar error. Coin
metal bulged into the crescentic gap and collided with the hammer
(obverse die) while simultaneously withdrawing from the anvil die. The
result is a crescent of die-struck design on the obverse face carrying
the legend united states of. The opposite face shows a deeply recessed
crescent devoid of design but marked by numerous microscopic stress
lines and a coarse, grainy texture.
I can envision additional scenarios that could generate an
Not all coins involved in the foregoing scenarios will develop
extrusion strikes. Scenarios 1 and 3 require striking pressure to be
slightly lower than normal. A slight reduction in ram pressure or an
increase in minimum die clearance will do the trick.
Coin World’s Collectors’ Clearinghouse department does
not accept coins or other items for examination without prior
permission from News Editor William T. Gibbs. Materials sent to
Clearinghouse without prior permission will be returned unexamined.
Please address all Clearinghouse inquiries to email@example.com or to
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